I am trying to power my Nikon DSLR with a permanent power source instead of the battery for long captures (overnight) without buying the overpriced battery adapter. I can't simply connect a AC-DC converter at correct voltage, as Nikon verifies the battery (or power source) and refuses to operate, if the power source is not verified. I have asked previously about a simple hack, which you can see here: simply connecting charger, battery and camera all together
This turns out to be bad, as charger's board might not handle the current spikes and the connection (charging? or not?). So the charger may be switched with a AC-DC converter. However, Nikon verifies the battery. I listened to the serial communication with a logic analyzer, which includes different data each time. I can't really decode it and if it is random, then cryptography is involved. More onto that you can find here. They even put FPGA chip inside the battery to handle verification (according to some blogs). I can't bypass the battery. However, I thought, I can use a bidirectional optocoupler to connect only the serial pin of the battery to the camera. That way, the voltage difference won't be an issue between the battery and power supply (as they will be isolated with an optocoupler) but camera will be able to communicate with the battery to verify it but won't have any clue, where the power is actually coming from.
The communication happens at 33333Hz (30μs for each bit) 3.3V logic between the battery and camera. Battery voltage can range between 7.2-8.2V. Original power adapter operat The optocoupler needs to handle 33333Hz at 3.3V. Since, I am not very familiar with power electronics and don't want to kill my camera, I would like to ask you, what can go wrong with this setup (before I try and destroy my camera)? How can I do this safely?